Method and apparatus for positioning a reference frame

ABSTRACT

A method and apparatus to perform a procedure that can include a processor assisted surgical procedure. During the procedure patient space and image space can be registered to allow for tracking of various tracking sensors. A dynamic reference frame can be used to maintain localization of the patient space with the image space. The dynamic reference frame can be fixedly interconnected with a bone portion of the anatomy.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.11/232,445 filed on Sep. 21, 2005, now U.S. Pat. No. 7,835,784. Theentire disclosure of the above application is incorporated herein byreference.

FIELD

The present disclosure relates generally to navigated surgery, and morespecifically, to a method and apparatus for performing a surgicalprocedure to repair, localize, and/or replace a selected portion of ananatomy.

BACKGROUND

Image guided medical and surgical procedures utilize patient imagesobtained prior to or during a medical procedure to guide a physicianperforming the procedure. Such procedures can be referred to as computerassisted procedures. Recent advances in imaging technology, especiallyin imaging technologies that produce highly-detailed, two, three, andfour dimensional images, such as computed tomography (CT), magneticresonance imaging (MRI), fluoroscopic imaging (such as with a C-armdevice), positron emission tomography (PET), and ultrasound imaging (US)has increased the interest in image guided medical procedures.

Typical image guided navigation systems generally require a dynamicreference frame to track the position of the patient should patientmovement occur during the assisted procedure. The dynamic referenceframe is generally affixed to the patient in a generally permanent orimmovable fashion. The dynamic reference frame may also be used as afiducial marker and may, therefore, be attached to the patient duringthe acquisition of pre-operative images. This enables the image space tobe aligned with patient space during the navigated procedure.

Various instruments that are desired to be tracked may be used during anoperative procedure. Image data is generally acquired, eitherintra-operatively or pre-operatively, and the instrument is generallyillustrated, and superimposed on the captured image data to identify theposition of the instrument relative to the patient space. Therefore, theinstrument may include tracking sensors, such as electromagnetic coilsor optical detection points, such as LEDs or reflectors that may bedetected by a suitable tracking system. Also, a dynamic reference frame(DRF) can be used by the tracking system to maintain a registration orlocalization of the patient space to the image space. The DRF can bealso any appropriate tracking sensor that is fixed to a portion of thepatient that allows the system to determine whether the patient hasmoved relative to the image space.

Other types of navigation systems operate as an image-less system, wherean image of the body is not captured by an imaging device prior to themedical procedure, such as the device disclosed in U.S. patentapplication Ser. No. 10/687,539, entitled Method And Apparatus ForSurgical Navigation Of A Multiple Piece Construct For Implantation,filed Oct. 16, 2003, incorporated herein by reference. With this type ofprocedure, the system may use a probe to contact certain landmarks inthe body, such as landmarks on bone, where the system generates either atwo-dimensional or three-dimensional model of the area of interest basedupon these contacts. This way, when the surgical instrument or otherobject is tracked relative to this area, they can be superimposed onthis model.

Generally, regardless of the whether the system is using images orimageless, a dynamic reference frame is used to maintain registration ofthe patient space with the navigated or image space. The position of thepatient can be determined in real time relative to the images, implant,instruments, etc. with the use of a dynamic reference frame.

Most types of orthopedic medical procedures are performed usingconventional surgical techniques, such as spine, hip, knee, shoulder, asynovial joint, and a facet joint. These techniques generally involveopening the patient in a manner to provide adequate viewing by thesurgeon during the medical procedure. Use of the navigated procedure mayenable more precise and accurate placement of an implant within thepatient and may also enable surgery with diminished visualization.

Although a dynamic reference frame can be attached to an external orskin portion of a patient, it may be desirable to attach the dynamicreference frame to a bone portion. Nevertheless, it is desirable toallow the dynamic reference frame to be easily yet fixedly attached tothe patient. It may also be desirable to fix the dynamic reference frameto the patient with a single member in an easy or simple procedure.

SUMMARY

According to various embodiments, a surgical navigation system to allowa processor assisted surgical procedure on an anatomy including a boneis disclosed. The system can include a tracking system operable to tracka tracking sensor. A dynamic reference frame can include a trackingsensor to be tracked by the tracking system. Also, a dynamic referenceframe positioning member can engage the bone in the anatomy toselectively fix the dynamic reference frame relative to the anatomy. Thedynamic reference frame positioning member can be driven into the boneto hold the dynamic reference frame in a selected position.

According to various embodiments a dynamic reference frame positioningmember can position a dynamic reference frame in a selected positionrelative to a bone. The positioning member can include a memberextending between a first end and a second end. The member can define adynamic reference frame engaging portion defined nearer the first endthan the second end. Also a bone engaging portion can extend from nearthe second end. The bone engaging portion can include a first member anda second member extending at an angle relative to one another. Also, thebone engaging portion can be driven into the bone.

According to various embodiments a method of using a dynamic referenceframe positioning member to position a dynamic reference frame relativeto a selected portion of an anatomy including a bone is disclosed. Themethod can includes positioning a cannula through a soft tissue portionof the anatomy relative to the bone portion. A dynamic reference framepositioning member can be positioned through the positioned cannula andpositioned into engagement with the bone. The dynamic reference framepositioning member can be fixed relative to the bone in at least one ofa rotational motion, axial motion, translation motion, or combinationthereof. Also, the cannula can be removed.

BRIEF DESCRIPTION OF THE DRAWINGS

The present teachings will become more fully understood from thedetailed description and the accompanying drawings, wherein:

FIG. 1 is a diagram of a navigation system according to variousteachings;

FIGS. 2A and 2B are diagrams representing undistorted and distortedviews from a fluoroscopic imaging device;

FIG. 3 is a positioning member according to various embodiments;

FIG. 4 is a positioning member according to various embodiments;

FIG. 5 is a positioning member according to various embodiments;

FIG. 6 is a kit including various instruments to perform a procedureaccording to various embodiments;

FIG. 7 is an environmental view of a dilator and cannula;

FIG. 8 is an environmental view of positioning a positioning memberaccording to various embodiments;

FIG. 9 is an environmental view of the removal of a positioning memberaccording to various embodiments;

FIG. 10 is a positioning member and tap cap according to variousembodiments; and

FIG. 11 is a modular tracking sensor connected to a positioning memberaccording to various embodiments.

DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS

The following description of various embodiments is merely exemplary innature and is in no way intended to limit the teachings, itsapplication, or uses. A method and apparatus to perform a procedure thatcan include a processor assisted surgical procedure. During theprocedure, patient space and image space can be registered to allow fortracking of various tracking sensors. A dynamic reference frame can beselectively interconnected with a portion of the anatomy to maintainlocalization of the patient space with the image space. Although thefollowing description describes the use of a dynamic reference framepositioning member in relation to a pelvis, it will be understood thatthe dynamic reference frame may be positioned in any portion of theanatomy. Further, the dynamic reference frame can be used for anorthopedic procedure, a spinal procedure, a cardiac procedure or anyother surgical or medical procedure.

FIG. 1 is a diagram illustrating an overview of an image-guidednavigation system 10 that can be used for various procedures. Thenavigation system 10 can be used to track the location of an implant,such as a spinal implant or orthopedic implant, relative to a patient14. Also the navigation system 10 can track the position and orientationof various instruments. It should further be noted that the navigationsystem 10 may be used to navigate any type of instrument, implant, ordelivery system, including: guide wires, arthroscopic systems,orthopedic implants, spinal implants, etc. Moreover, these instrumentsmay be used to navigate or map any region of the body. The navigationsystem 10 and the various instruments may be used in any appropriateprocedure, such as one that is generally minimally invasive or an openprocedure.

The navigation system 10 may include an optional imaging device 12 thatis used to acquire pre-, intra-, or post-operative or real-time imagedata of a patient 14. Alternatively various imageless systems can beused or images from atlas models can be used to produce patient images,such as those disclosed in U.S. patent application Ser. No. 10/687,539,filed Oct. 16, 2003, entitled “METHOD AND APPARATUS FOR SURGICALNAVIGATION OF A MULTIPLE PIECE CONSTRUCT FOR IMPLANTATION”, incorporatedherein by reference. The optional imaging device 12 is, for example, afluoroscopic x-ray imaging device that may be configured as a C-arm 16having an x-ray source 18, an x-ray receiving section 20, an optionalcalibration and tracking target 22 and optional radiation sensors 24.

Image data may also be acquired using other imaging devices, such asthose discussed above and herein. The calibration and tracking target 22includes calibration markers 26 (see FIGS. 2A-2B), further discussedherein. An optional imaging device controller 28, that may control theC-arm 16, can capture the x-ray images received at the receiving section20 and store the images for later use. The controller 28 may also beseparate from the C-arm 16 and/or control the rotation of the C-arm 16.For example, the C-arm 16 can move in the direction of arrow 30 orrotate about a longitudinal axis 14 a of the patient 14, allowinganterior or lateral views of the patient 14 to be imaged. Each of thesemovements involves rotation about a mechanical axis 32 of the C-arm 16.

In the example of FIG. 1, the longitudinal axis 14 a of the patient 14is substantially in line with the mechanical axis 32 of the C-arm 16.This enables the C-arm 16 to be rotated relative to the patient 14,allowing images of the patient 14 to be taken from multiple directionsor about multiple planes. An example of a fluoroscopic C-arm x-raydevice that may be used as the optional imaging device 12 is the “Series9600 Mobile Digital Imaging System,” from OEC Medical Systems, Inc., ofSalt Lake City, Utah. Other exemplary fluoroscopes include bi-planefluoroscopic systems, ceiling fluoroscopic systems, cath-labfluoroscopic systems, fixed C-arm fluoroscopic systems, isocentric C-armfluoroscopic systems, 3D fluoroscopic systems, etc.

In operation, the imaging device 12 generates x-rays from the x-raysource 18 that propagate through the patient 14 and calibration and/ortracking target 22, into the x-ray receiving section 20. It will beunderstood that the tracking target need not include a calibrationportion. The receiving section 20 generates image data representing theintensities of the received x-rays. Typically, the receiving section 20includes an image intensifier that first converts the x-rays to visiblelight and a charge coupled device (CCD) video camera that converts thevisible light into digital image data. Receiving section 20 may also bea digital device that converts x-rays directly to digital image data forforming images, thus potentially avoiding distortion introduced by firstconverting to visible light. With this type of digital C-arm, which isgenerally a flat panel device, the optional calibration and/or trackingtarget 22 and the calibration process discussed below may be eliminated.Also, the calibration process may be eliminated or not used at all forvarious procedures. Alternatively, the imaging device 12 may only take asingle image with the calibration and tracking target 22 in place.Thereafter, the calibration and tracking target 22 may be removed fromthe line-of-sight of the imaging device 12.

Two dimensional fluoroscopic images that may be taken by the imagingdevice 12 are captured and stored in the C-arm controller 28. Multipletwo-dimensional images taken by the imaging device 12 may also becaptured and assembled to provide a larger view or image of a wholeregion of a patient, as opposed to being directed to only a portion of aregion of the patient. For example, multiple image data of a patient'sleg may be appended together to provide a full view or complete set ofimage data of the leg that can be later used to follow contrast agent,such as Bolus tracking.

The image data is then forwarded from the C-arm controller 28 to anavigation computer and/or processor controller or work station 34having a display 36 and a user interface 38. It will also be understoodthat the image data is not necessarily first retained in the controller28, but may also be directly transmitted to the navigation computer 34.The work station 34 provides facilities for displaying the image data asan image on the display 36, saving, digitally manipulating, or printinga hard copy image of the of the received image data. The user interface38, which may be a keyboard, mouse, touch pen, touch screen or othersuitable device, allows a physician or user to provide inputs to controlthe imaging device 12, via the C-arm controller 28, or adjust thedisplay settings of the display 36. The work station 34 may also directthe C-arm controller 28 to adjust the rotational axis 32 of the C-arm 16to obtain various two-dimensional images along different planes in orderto generate representative two-dimensional and three-dimensional images.

When the x-ray source 18 generates the x-rays that propagate to thex-ray receiving section 20, the radiation sensors 24 sense the presenceof radiation, which is forwarded to the C-arm controller 28, to identifywhether or not the imaging device 12 is actively imaging. Thisinformation is also transmitted to a coil array controller 48, furtherdiscussed herein. Alternatively, a person or physician may manuallyindicate when the imaging device 12 is actively imaging or this functioncan be built into the x-ray source 18, x-ray receiving section 20, orthe control computer 28.

The optional imaging device 12, such as the fluoroscopic C-arm 16, thatdo not include a digital receiving section 20 generally require theoptional calibration and/or tracking target 22. This is because the rawimages generated by the receiving section 20 tend to suffer fromundesirable distortion caused by a number of factors, including inherentimage distortion in the image intensifier and external electromagneticfields. An empty undistorted or ideal image and an empty distorted imageare shown in FIGS. 2A and 2B, respectively. The checkerboard shape,shown in FIG. 2A, represents the ideal image 40 of the checkerboardarranged calibration markers 26. The image taken by the receivingsection 20, however, can suffer from distortion, as illustrated by thedistorted calibration marker image 42, shown in FIG. 2B.

Intrinsic calibration, which is the process of correcting imagedistortion in a received image and establishing the projectivetransformation for that image, involves placing the calibration markers26 in the path of the x-ray, where the calibration markers 26 are opaqueor semi-opaque to the x-rays. The calibration markers 26 are rigidlyarranged in pre-determined patterns in one or more planes in the path ofthe x-rays and are visible in the recorded images. Because the truerelative position of the calibration markers 26 in the recorded imagesare known, the C-arm controller 28 or the work station or computer 34 isable to calculate an amount of distortion at each pixel in the image(where a pixel is a single point in the image). Accordingly, thecomputer or work station 34 can digitally compensate for the distortionin the image and generate a distortion-free or at least a distortionimproved image 40 (see FIG. 2A). A more detailed explanation ofexemplary methods for performing intrinsic calibration are described inthe references: B. Schuele, et al., “Correction of Image IntensifierDistortion for Three-Dimensional Reconstruction,” presented at SPIEMedical Imaging, San Diego, Calif., 1995; G. Champleboux, et al.,“Accurate Calibration of Cameras and Range Imaging Sensors: the NPBSMethod,” Proceedings of the IEEE International Conference on Roboticsand Automation, Nice, France, May, 1992; and U.S. Pat. No. 6,118,845,entitled “System And Methods For The Reduction And Elimination Of ImageArtifacts In The Calibration Of X-Ray Imagers,” issued Sep. 12, 2000,the contents of which are each hereby incorporated by reference.

While the optional imaging device 12 is shown in FIG. 1, any otheralternative 2D, 3D or 4D imaging modality may also be used. For example,any 2D, 3D or 4D imaging device, such as isocentric fluoroscopy,bi-plane fluoroscopy, ultrasound, computed tomography (CT), multi-slicecomputed tomography (MSCT), magnetic resonance imaging (MRI), highfrequency ultrasound (HIFU), positron emission tomography (PET), opticalcoherence tomography (OCT), intra-vascular ultrasound (IVUS),ultrasound, intra-operative CT or MRI may also be used to acquire 2D, 3Dor 4D pre- or post-operative and/or real-time images or image data ofthe patient 14. The images may also be obtained and displayed in two,three or four dimensions. In more advanced forms, four-dimensionalsurface rendering regions of the body may also be achieved byincorporating patient data or other data from an atlas or anatomicalmodel map or from pre-operative image data captured by MRI, CT, orechocardiography modalities. A more detailed discussion on opticalcoherence tomography (OCT), is set forth in U.S. Pat. No. 5,740,808,issued Apr. 21, 1998, entitled “Systems And Methods For GuildingDiagnostic Or Therapeutic Devices In Interior Tissue Regions” which ishereby incorporated by reference.

Image datasets from hybrid modalities, such as positron emissiontomography (PET) combined with CT, or single photon emission computertomography (SPECT) combined with CT, could also provide functional imagedata superimposed onto anatomical data to be used to confidently reachtarget sights within the patient 14. It should further be noted that theoptional imaging device 12, as shown in FIG. 1, provides a virtualbi-plane image using a single-head C-arm fluoroscope as the optionalimaging device 12 by simply rotating the C-arm 16 about at least twoplanes, which could be orthogonal planes to generate two-dimensionalimages that can be converted to three-dimensional volumetric images. Byacquiring images in more than one plane, an icon representing thelocation of an impacter, stylet, reamer driver, taps, drill, or otherinstrument, introduced and advanced in the patient 14, may besuperimposed in more than one view on display 36 allowing simulatedbi-plane or even multi-plane views, including two and three-dimensionalviews.

These types of imaging modalities may provide certain distinct benefitsfor their use. For example, magnetic resonance imaging (MRI) isgenerally performed pre-operatively using a non-ionizing field. Thistype of imaging provides very good tissue visualization inthree-dimensional form and also provides anatomy and functionalinformation from the imaging. MRI imaging data is generally registeredand compensated for motion correction using dynamic reference frames(DRF) discussed further herein.

Positron emission tomography (PET) imaging is generally a pre-operativeimaging procedure that exposes the patient to some level of radiation toprovide a 3D image. PET imaging provides functional information and alsogenerally requires registration and motion correction using dynamicreference frames.

Computed tomography (CT) imaging is also generally a pre-operativetechnique that exposes the patient to a limited level of radiation. CTimaging, however, is a very fast imaging procedure. A multi-slice CTsystem provides 3D images having good resolution and anatomyinformation. Again, CT imaging is generally registered and needs toaccount for motion correction, via dynamic reference frames.

Fluoroscopy imaging is generally an intra-operative imaging procedurethat exposes the patient to certain amounts of radiation to provideeither two-dimensional or rotational three-dimensional images.Fluoroscopic images generally provide good resolution and anatomyinformation. Fluoroscopic images can be either manually or automaticallyregistered and also need to account for motion correction using dynamicreference frames.

Ultrasound imaging is also generally intra-operative procedure using anon-ionizing field to provide 2D, 3D, or 4D imaging, including anatomyand blood flow information. Ultrasound imaging provides automaticregistration and does not need to account for any motion correction.

With continuing reference to FIG. 1, the navigation system 10 canfurther include an electromagnetic navigation or tracking system 44 thatincludes a localizer, such as a transmitter coil array 46, the coilarray controller 48, a navigation probe interface 50, an instrument 52and a dynamic reference frame 54. The dynamic reference frame 54 can beinterconnected with a removable tracking sensor 54 a or can include amore integral tracking sensor 54 aa and a dynamic reference framepositioning member 80, according to various embodiments. It will beunderstood that reference to either the tracking sensor 54 a or theintegral tracking sensor 54 aa can be a reference to either, unlessspecifically taught otherwise. Generally, the tracking sensor 54 aa istracked by the navigation system and the dynamic reference framepositioning member 80 fixes, as discussed further herein, the trackingsensor 54 aa relative to the patient 14.

The instrument 52 may be any appropriate instrument, such as aninstrument for preparing a portion of the patient or positioning animplant. The transmitter coil array 46 may also be supplemented orreplaced with a mobile localizer 46 a. The mobile localizer 46 a may beone such as that described in U.S. patent application Ser. No.10/941,782, filed Sep. 15, 2004, and entitled “METHOD AND APPARATUS FORSURGICAL NAVIGATION”, herein incorporated by reference. It will beunderstood that the tracking system may be any appropriate trackingsystem, such as an optical localizer illustrated in phantom at 47 suchas the StealthStation® TRIA™ sold by Medtronic Navigation of Louisville,Colo. Other localization systems include an acoustic, radiation etc.

Further included in the navigation system 10 may be an isolator circuitor box 55. The isolator circuit or box 55 may be included in atransmission line to interrupt a line carrying a signal or a voltage tothe navigation probe interface 50. Alternatively, the isolator circuitincluded in the isolator box 55 may be included in the navigation probeinterface 50, the instrument 52, the dynamic reference frame 54, thetransmission lines coupling the devices, or any other appropriatelocation. The isolator box 55 is operable to isolate any of theinstruments or patient coincidence instruments or portions that are incontact with the patient should an undesirable electrical surge orvoltage take place.

It should further be noted that the entire tracking system 44 or partsof the tracking system 44 may be incorporated into the imaging device12, including the work station 34 and radiation sensors 24.Incorporating the tracking system 44 may provide an integrated imagingand tracking system. Any combination of these components may also beincorporated into the imaging system 12, which again can include afluoroscopic C-arm imaging device or any other appropriate imagingdevice.

The transmitter coil array 46 is shown attached to the receiving section20 of the C-arm 16. It should be noted, however, that the transmittercoil array 46 may also be positioned at any other location as well. Forexample, the transmitter coil array 46 may be positioned at the x-raysource 18, within or atop the OR table 56 positioned below the patient14, on siderails associated with the table 56, or positioned on thepatient 14 in proximity to the region being navigated, such as on thepatient's chest. The transmitter coil array 46 may also be positioned inthe items being navigated, further discussed herein. The transmittercoil array 46 includes a plurality of coils that are each operable togenerate distinct electromagnetic fields into the navigation region ofthe patient 14, which is sometimes referred to as patient space.Representative electromagnetic systems are set forth in U.S. Pat. No.5,913,820, entitled “Position Location System,” issued Jun. 22, 1999 andU.S. Pat. No. 5,592,939, entitled “Method and System for Navigating aCatheter Probe,” issued Jan. 14, 1997, each of which are herebyincorporated by reference.

The transmitter coil array 46 is controlled or driven by the coil arraycontroller 48. The coil array controller 48 drives each coil in thetransmitter coil array 46 in a time division multiplex or a frequencydivision multiplex manner. In this regard, each coil may be drivenseparately at a distinct time or all of the coils may be drivensimultaneously with each being driven by a different frequency. Upondriving the coils in the transmitter coil array 46 with the coil arraycontroller 48, electromagnetic fields are generated within the patient14 in the area where the medical procedure is being performed, which isagain sometimes referred to as patient space. The electromagnetic fieldsgenerated in the patient space induce currents in a sensor 58 positionedon or in the instrument 52. These induced signals from the instrument 52are delivered to the navigation probe interface 50 through the isolationcircuit 55 and subsequently forwarded to the coil array controller 48.The navigation probe interface 50 may provide all the necessaryelectrical isolation for the navigation system 10. Alternatively, theelectrical isolation may also be provided in the isolator box 55.Nevertheless, the isolator assembly 55 may be included in the navigationprobe interface 50 or may be integrated into the instrument 52, and anyother appropriate location. The navigation probe interface 50 can alsoinclude amplifiers, filters and buffers to directly interface with thesensors 58 in the instrument 52. Alternatively, the instrument 52 mayemploy a wireless communications channel, such as that disclosed in U.S.Pat. No. 6,474,341, entitled “Surgical Communication Power System,”issued Nov. 5, 2002, herein incorporated by reference, as opposed tobeing coupled directly to the navigation probe interface 50.

Various portions of the navigation system 10, such as the instrument 52,the dynamic reference frame (DRF) 54, the probe 66, and others as willbe described in detail below, are equipped with at least one, andgenerally multiple, tracking sensors 58, that may also be referred to aslocalization sensors. The instrument 52 can be a handle or inserter thatinterconnects with an attachment and may assist in placing an implant orin driving a portion. The instrument 52 can include a graspable ormanipulable portion at a proximal end and the tracking sensor 58 may befixed near the manipulable portion of the instrument 52. The trackingsensor 58 may be any appropriate tracking sensor 58 such as an opticalsensor, acoustic sensor, or an electromagnetic sensor. If the sensor 58includes an electromagnetic sensor the electromagnetic field generatedby the transmitter coil array 46 may induce a current in theelectromagnetic sensor 58. An alternative sensor may include an opticalsensor, such as the optical sensor 58 a, and may be used in addition toor in place of the electromagnetic sensor 58. The optical sensor maywork with the optional optical array 47.

In an alternate embodiment, the electromagnetic sources or generatorsmay be located within the instrument 52, DRF 54 (such as the integraltacking sensor 54 aa), probe 66 and one or more receiver coils may beprovided externally to the patient 14 forming a receiver coil arraysimilar to the transmitter coil array 46. In this regard, the trackingsensors 58 could generate electromagnetic fields that would be receivedby the receiving coils in the receiving coil array similar to thetransmitter coil array 46. Other types of tracking systems includeoptical, acoustic, electrical field, RF and accelerometers.Accelerometers enable both dynamic sensing due to motion and staticsensing due to gravity. An additional representative alternativelocalization and tracking system is set forth in U.S. Pat. No.5,983,126, entitled “Catheter Location System and Method,” issued Nov.9, 1999, which is hereby incorporated by reference. Alternatively, thelocalization system may be a hybrid system that includes components fromvarious systems.

The dynamic reference frame 54 of the tracking system 44 is also coupledto the navigation probe interface 50 to forward the information to thecoil array controller 48. The dynamic reference frame 54, according tovarious embodiments, may include a small magnetic field detector. Thedynamic reference frame 54 may be fixed to the patient 14 adjacent tothe region being navigated so that any movement of the patient 14 isdetected as relative motion between the transmitter coil array 46 andthe dynamic reference frame 54. The dynamic reference frame 54 can beinterconnected with the patient in any appropriate manner, includingthose discussed herein. This relative motion is forwarded to the coilarray controller 48, which updates registration correlation andmaintains accurate navigation, further discussed herein. The dynamicreference frame 54 may be any appropriate tracking sensor used as thedynamic reference frame 54 in the navigation system 10. Therefore thedynamic reference frame 54 may also be optical, acoustic, etc. If thedynamic reference frame 54 is electromagnetic it can be configured as apair of orthogonally oriented coils, each having the same center or maybe configured in any other non-coaxial or co-axial coil configurations.

The dynamic reference frame 54 may be affixed externally to the patient14, adjacent to the region of navigation, such as on the patient's chestor pelvis, as shown in FIG. 1. The dynamic reference frame 54 can beaffixed to the patient's skin, by way of a selected adhesive patchand/or a tensioning system. The dynamic reference frame 54 may also beremovably attachable to fiducial markers 60 also positioned on thepatient's body and further discussed herein. The dynamic reference frame54 can also be connected to a bone portion of the anatomy. The boneportion can be adjacent, the area of the procedure, the bone of theprocedure, or any appropriate bone portion.

The dynamic reference frame 54 may also be attached to various boneyportions such as a femur, pelvis, cranium, or other boney portions. Themovement of various portions, such as the instrument 52, relative tothese boney portions can then be determined, even if the boney portionis also moved. This may assist in positioning an implant or inperforming a planned procedure.

Briefly, the navigation system 10 operates as follows. The navigationsystem 10 creates a translation map between all points in theradiological image generated from the imaging device 12 and thecorresponding points in the patient's anatomy in patient space. Afterthis map is established, whenever a tracked instrument, such as theinstrument 52 or a pointing device or probe 66 is used, the work station34 in combination with the coil array controller 48 and the C-armcontroller 28 uses the translation map to identify the correspondingpoint on the pre-acquired image or atlas model, which is displayed ondisplay 36. This identification is known as navigation or localization.An icon representing the localized point or instruments is shown on thedisplay 36 within several two-dimensional image planes, as well as onthree and four dimensional images and models.

To enable navigation, the navigation system 10 must be able to detectboth the position of the patient's anatomy and the position of theinstrument 52 or attachment member attached to the instrument 52.Knowing the location of these two items allows the navigation system 10to compute and display the position of the instrument 52 in relation tothe patient 14. The tracking system 44 is employed to track theinstrument 52 and the anatomy simultaneously.

The tracking system 44, if it is using an electromagnetic trackingassembly, essentially works by positioning the transmitter coil array 46adjacent to the patient space to generate a low-energy magnetic fieldgenerally referred to as a navigation field. Because every point in thenavigation field or patient space is associated with a unique fieldstrength, the electromagnetic tracking system 44 can determine theposition of the instrument 52 by measuring the field strength at thetracking sensor 58 location. The dynamic reference frame 54 is fixed tothe patient 14 to identify the location of the patient in the navigationfield. The electromagnetic tracking system 44 continuously recomputesthe relative position of the dynamic reference frame 54 and theinstrument 52 during localization and relates this spatial informationto patient registration data to enable image guidance of the instrument52 within and/or relative to the patient 14.

Patient registration is the process of determining how to correlate theposition of the instrument 52 relative to the patient 14 to the positionon the diagnostic or pre-acquired images. To register the patient 14, aphysician or user 67 may use point registration by selecting and storingparticular points from the pre-acquired images and then touching thecorresponding points on the patient's anatomy with the pointer probe 66.The navigation system 10 analyzes the relationship between the two setsof points that are selected and computes a match, which correlates everypoint in the image data with its corresponding point on the patient'sanatomy or the patient space. The points that are selected to performregistration are the fiducial markers or landmarks 60, such asanatomical landmarks. Again, the landmarks or fiducial points 60 areidentifiable on the images and identifiable and accessible on thepatient 14. The landmarks 60 can be artificial landmarks 60 that arepositioned on the patient 14 or anatomical landmarks that can be easilyidentified in the image data. The artificial landmarks, such as thefiducial markers 60, can also form part of the dynamic reference frame54, such as those disclosed in U.S. Pat. No. 6,381,485, entitled“Registration of Human Anatomy Integrated for ElectromagneticLocalization,” issued Apr. 30, 2002, herein incorporated by reference.

The system 10 may also perform registration using anatomic surfaceinformation or path information as is known in the art. The system 10may also perform 2D to 3D registration by utilizing the acquired 2Dimages to register 3D volume images by use of contour algorithms, pointalgorithms or density comparison algorithms, as is known in the art. Anexemplary 2D to 3D registration procedure, is set forth in U.S. Ser. No.60/465,615, entitled “Method and Apparatus for Performing 2D to 3DRegistration” filed on Apr. 25, 2003, hereby incorporated by reference.

In order to maintain registration accuracy, the navigation system 10continuously tracks the position of the patient 14 during registrationand navigation. This is because the patient 14, dynamic reference frame54, and transmitter coil array 46 may all move during the procedure,even when this movement is not desired. Therefore, if the navigationsystem 10 did not track the position of the patient 14 or area of theanatomy, any patient movement after image acquisition would result ininaccurate navigation within that image. The dynamic reference frame 54allows the electromagnetic tracking device 44 to register and track theanatomy. Because the dynamic reference frame 54 is rigidly fixed to thepatient 14, any movement of the anatomy or the transmitter coil array 46is detected as the relative motion between the transmitter coil array 46and the dynamic reference frame 54. This relative motion is communicatedto the coil array controller 48, via the navigation probe interface 50,which updates the registration correlation to thereby maintain accuratenavigation.

The navigation system 10 can be used according to any appropriate methodor system. For example, pre-acquired images, atlas or 3D models may beregistered relative to the patient and patient space. Generally, thenavigation system allows the images on the display 36 to be registeredand accurately display the real time location of the variousinstruments, such as the instrument 52, and other appropriate items,such as the pointer 66. In addition, the pointer 66 may be used toregister the patient space to the pre-acquired images or the atlas or 3Dmodels. In addition, the dynamic reference frame 54 may be used toensure that any planned or unplanned movement of the patient or thereceiver array 46 is determined and used to correct the image on thedisplay 36.

With additional reference to FIG. 3, the dynamic reference frame 54 canbe affixed to any appropriate portion of the patient 14, and can be usedto register the patient to the image data, as discussed above. Forexample, when a spinal procedure is being performed, the dynamicreference frame 54 can be interconnected with a portion of a spine 15 ofthe patient. The spine 15 can include various vertebral bodies 15 a andportions of the vertebral bodies. In addition, or alternatively, thedynamic reference frame 54 can be affixed to any appropriate portion ofthe patient 14. The dynamic reference frame 54 can be interconnectedwith a portion of a pelvis 17 of the patient 14. The dynamic referenceframe 54 can be interconnected with the pelvis 17 in any appropriatemanner, such as those discussed herein according to various embodiments.

Affixing the dynamic reference frame 54 to the pelvis can be appropriateif the procedure being performed is performed in a portion of theanatomy that is held substantially still or stable relative to thepelvis 17. For example, various portions of the lumbar spine 15 are heldsubstantially constant relative to the pelvis 17. In other words, if thepelvis 17 moves a selected amount, the selected lumbar vertebrae 15 aare held at a substantially constant distance relative to the pelvis 17.Therefore, it would be understood that the dynamic reference frame 54can be interconnected with any selected portion of the anatomy.

To obtain a maximum reference it can be selected to fix the dynamicreference frame 54 in each of at least 6 degrees of freedom. Thus, thedynamic reference frame 54 can be fixed relative to axial motion X,translational motion Y, rotational motion Z, yaw, pitch, and rollrelative to the portion of the patient 14 to which it is attached. Anyappropriate coordinate system can be used to describe the variousdegrees of freedom. Fixing the dynamic reference frame relative to thepatient 14 in this manner can assist in maintaining maximum accuracy ofthe navigation system 10.

With additional reference to FIG. 3, a dynamic reference frame fixationdevice 80 according to various embodiments is illustrated. The dynamicreference frame fixation device 80 generally includes a body 82 thatextends between a first or proximal end 84 and a distal or second end86. Extending from the distal end 86 is a bone engaging or fixationsection 88. The bone engaging section 88 can be provided to engage aselected portion of the bone or another portion of the anatomy, such asthe pelvis 17. It will also be understood that the bone engaging portion88 can be provided to engage a portion of the anatomy other than bone.

The bone engaging section 88 can be formed in any appropriate manner,but can include at least a first arm or portion 90 and a second arm orportion 92 and may also include a third arm portion 94 and a fourth armportion 96. Generally, at least two of the arm portions 90 and 92 can beprovided. Though any appropriate number, such as the third and fourtharm portions 94, 96, or more can also be provided. The arm portions90-96 engage the bone, such as the pelvis 17 can resist rotation of thedynamic reference frame fixation member 80.

Further, a distal end 98 of the bone engaging section 88 can be formedin any appropriate manner. Generally, the distal end 98 can besharpened, such that the dynamic reference frame fixation member 80 canbe driven into the selected bone portion, such as with a hammer. Thebone engaging section can be sharpened in any appropriate manner so thata generally straight axial motion can drive the dynamic reference framefixation member 80 into the bone. In other words, the distal end 98 canallow the dynamic reference frame fixation member 80 to be driven intothe bone with a hammer or similar device, such that a rotation of thedynamic reference frame fixation member 80 is not required.

The body 82 can include any appropriate dimension, which may be asimilar dimension to the bone engaging section 88. For example, the boneengaging section 88 can include a large or largest dimension A thatdefines the width between the ends of the first arm 90 and the third arm94. Nevertheless, if two arms, such as arm 90, 92 are provided atsubstantially right angles to one another, the largest dimension may besmaller than the dimension A. Nevertheless, the dimension A may be about1.5 mm to about 10 mm.

The dimension A can also be the largest dimension in the body 82. Thiscan allow the dynamic reference frame fixation member 80 to be passedthrough a small incision or puncture wound in a soft tissue of thepatient 14. This can allow the dynamic reference frame fixation member80 to be implanted or positioned substantially percutaneously or througha very small incision. Also, as discussed herein, the dynamic referenceframe fixation member 80 can be positioned in the anatomy through apuncture wound formed with a dilator and cannula.

Further, near the proximal end 84 of the body 82, a dynamic referenceframe holding portion 100 can be provided. The dynamic reference frameholding portion 100 can include a bore or opening 102 that canselectively engage the tracking sensor 54 a. Further, the dynamicreference frame holding section 100 can include a second bore 104 tofurther fix the tracking sensing 54 a. Further, or in addition to thetracking sensor 54 a, the integral or included tracking sensor that canact as a tracking sensor 54 aa can be included in the body 82. Theincluded tracking sensor 54 aa can be an electromagnetic trackingsensor. The included or one piece tracking sensor 54 aa can act as thetracking sensor for the dynamic reference frame so that an additionalone need not be interconnected with the body 82. Nevertheless, it willbe understood that any appropriate tracking sensor can be used as thedynamic reference frame, such as an electromagnetic tracking sensor, anacoustic tracking sensor, a nuclear tracking sensor, an optical or IRtracking sensor, or combinations thereof. The dynamic reference framepositioning member 80 can be provided to interconnect the dynamicreference frame with the bony portion, regardless whether the dynamicreference frame is selectively interconnected with the body 82 or formedwith or in the body 82.

If the tracking sensor 54 a is provided it can be interconnected withthe dynamic reference frame holding portion 100. For example thetracking sensor can be formed as a shape that compliments the dynamicreference frame holding portion 100 such that positioning the trackingsensor 54 a into the dynamic reference frame holding portion 100 fixesit relative to the body 82. Further, screws or pins can be provided tofurther interconnect the tracking sensor 54 a with the dynamic referenceframe holding portion 100. Alternatively, the locking screw 170 (FIG. 6)can engage any appropriate of the bores 102, 104 to fix the trackingsensor 54 a relative to the body 82.

With reference to FIG. 4, a dynamic reference frame positioning member110 according to various embodiments is illustrated. The dynamicreference frame positioning member 110 includes portions that aresimilar to those illustrated in the dynamic reference frame positioningmember 80 illustrated in FIG. 3 and like reference numerals are used toreference like portions.

Extending from the distal end 86 of the dynamic reference framepositioning member 110 is a bone engaging section or portion 112. Thebone engaging section 112 can include a extending member 114 thatextends from the distal end 86. The extending member 114 can include asubstantially smooth portion 116 and a second portion 118 from whichbone engaging fins 120, 122, 124, and 126. It will be understood,similar to the bone engaging portion 88, that any appropriate number offins may be provided and four is merely provided as an example. Thesmooth portion 116 can terminate in a blunted or sharpened end.

The bone engaging portion 112 can be driven into the bone similar to thebone engaging portion 88. Therefore, the smooth end 116 may include asharpened or bone driving portion so that the dynamic reference framepositioning member 110 can be driven into a selected portion of theanatomy, such as the pelvis 17. Similar to the bone engaging portion 88,the bone engaging portion 112 can allow the dynamic reference framepositioning member 110 to be hammered or impacted to be driven axiallyinto the bone. Therefore, the dynamic reference frame positioning member110 need not be screwed or rotated to drive the dynamic reference framepositioning member 110 into the bone. The various fins 120, 122, 124,126 can be sharpened on the distal portion thereof to assist in drivingthe dynamic reference frame positioning member 110 into the selectedportion of the anatomy.

Further, the various fins 120, 122, 124, 126 can engage the bone tosubstantially resist rotation of the dynamic reference frame positioningmember 110 after insertion thereof. Therefore, the tracking sensor 54 a,54 aa interconnected with the dynamic reference frame positioning member110 can be held relative to the bone in a selected manner, such as toresist rotation, translation, axial movement, and movement in pitch,yaw, and roll. Also the dynamic reference frame positioning member 110can have an included or one piece tracking sensor 54 aa, similar to thatof the dynamic reference frame positioning member 80. Thus, the separateor modular tracking sensor 54 a may not be used. Further, either or bothof the dynamic reference frames can be any appropriate tracking sensor,such as those discussed above and herein.

With reference to FIG. 5, a dynamic reference frame positioning member130 is illustrated. The dynamic reference frame positioning member 130includes a body 132 that extends between a first or distal end 134 and asecond or proximal end 136. Near the second end 136 is a dynamicreference frame positioning portion 135. The dynamic reference framepositioning portion 135 can be formed in any appropriate manner, such asthe dynamic reference frame positioning portion 100 illustrated in thedynamic reference frame positioning members 80, 110. Nevertheless, thedynamic reference frame positioning portion 135 can include a selectedgeometry, such as a hexagon, square, cylindrical or the like, that canbe interconnected with the tracking sensor 54 a, such as that discussedherein. For example the locking screw 170 (FIG. 6) can contact one ofthe flats of the dynamic reference frame positioning portion 135 toholding the tracking sensor 54 a relative thereto. Although it will beunderstood that an included or one-piece tracking sensor 54 aa may beprovided in the dynamic reference frame positioning member 130.

The dynamic reference frame positioning member 130 also includes a boneengaging portion 138 that extends from the first end 134. Similar to thebone engaging portion 88, the bone engaging portion of 138 can includeany appropriate number of fins 138 such as a first fin 138 a, a secondfin 138 b, a third fin 138 c and a fourth fin 138 d. It will beunderstood that any appropriate number of the fins 138 can be provided.The fins 138 can include sharpened edges and sharpened ends to assist intheir movement into a selected bone portion. As discussed herein, thedynamic reference frame positioning member 130 may be drivensubstantially axially, such as with an impacting motion, into theselected bone portion. Further, as discussed herein, the selected numberof fins or geometry of the fins 138 can provide for a reduction orelimination or rotation of the dynamic reference frame positioningmember 130.

It will be understood that the dynamic reference frame positioningmembers 80, 110, 130, can be used according to any appropriateembodiments and any selected procedure. Further, the selection of thedynamic reference frame positioning member 80, 110, 130 can be for theprocedure, selection by a user, inclusion of the selected kit, or thelike. Therefore, it will be understood that the dynamic reference framepositioning member 80, 110, 130 can be used according to any appropriatereason.

The dynamic reference frame positioning members 80, 110, 130 caninterconnect a selected tracking sensor, such as an optical reflectivetracking sensor 54 a or an electromagnetic tracking sensor 54 aa thatcan be interconnected or formed in the body 82, relative to the anatomy.Therefore, the dynamic reference frame positioning members 80, 110, 130can be driven through substantially small or puncture wounds of the softtissue to engage a selected portion of the anatomy, especially bonyportions therein. This can allow the tracking sensor 54 a, 54 aa to beheld relative to a selected portion of the anatomy by providing thedynamic reference frame positioning member 80, 110, 130 through a smallincision with a hammer force or other similar force producing device.

It can also be understood, according to various embodiments, thatregistration techniques can be used to determine the position of thedynamic reference frame 54 relative to any portion of the selecteddynamic reference frame positioning member 80, 110, 130. For example theprobe 66 can be tracked and touched to the first end of the respectivedynamic frame positioning member 80, 110, 130 so that the navigationsystem 10 can determine the position of the anatomy. Alternatively, orin addition there to, such information can be preprogrammed or stored inthe navigation system 10.

Also, the dynamic reference frame 54 can include a fiducial portion. Thefiducial portion can be formed into the tracking sensor 54 a, thedynamic reference frame positioning member 80, 110, 130, or anyappropriate portion. For example a dimple can be formed in the dynamicreference frame that the probe 66 can touch. This can allow forregistration of the patient space to the image space. Further, it willbe understood that the fiducial portion of the dynamic reference 54 canbe formed with or separate from any other portion of the dynamicreference frame.

With reference to FIG. 6, the dynamic reference frame positioning member80 can be provided in a kit 150 that can include a plurality ofinstruments or portions. It will be understood that the kit 150 can beunderstood as a system for positioning the dynamic reference frame 54and/or a part of the navigation system 10. Further, the kit 150 caninclude all, part, or more parts than those illustrated and discussed.It will be understood that the dynamic reference frame positioningmember 110 and/or 130 can also be provided in addition to or in thealternative of the dynamic reference frame positioning member 80, andonly one is shown for clarity of the following discussion. The variousportions included in the kit 150 can include any appropriate portions,and only exemplary include those described herein. Therefore, it will beunderstood that the portions of the kit 150 described herein are merelyexemplary and not intended to limit the scope of the present teachings.

Regardless the kit 150 can include the dynamic reference framepositioning member 80 (which can also be referenced as a percutaneousreference pin). Further, the kit 150 can include the tracking sensor 54a, which can be interconnected with the dynamic reference framepositioning member 80. It will be understood, however, that the dynamicreference frame positioning member 80 may have included therein thetracking sensor 54 aa.

The kit 150 may also include a tap cap 152, a cannula 154, a dilator156, an impactor 157, and a slap hammer 158. The various portions of thekit 150 can be used according to any appropriate embodiment. Further,the portions of the kit 150 can be selected to include selectedfeatures. For example the cannula 154 can be flexible, rigid, or acombination thereof. Also, the kit 150 may be used according to a methodas exemplary described herein. Therefore, it will be understood that theportions of the kit 150 may be used with any appropriate system ormethod and the method described herein is merely exemplary.

It will be understood that each of the portions of the kit 150 may besubstantially single use and can be disposed of after a selectedprocedure. Nevertheless, it will be understood that the various portionsof the kit 150 may also be multi-use and used for a plurality ofprocedures. Regardless, various portions of the kit 150, such as thedynamic reference frame positioning member 80, can be formed of anyappropriate materials, such as various metals or metal alloys, polymers,or any other appropriate materials. The various portions of the kit 150,such as the dynamic reference frame positioning member 80 can besterilized according to various procedures to reduce or eliminate thepossibility of contamination or infection during use. Further the kit150 can be provided in a container 159 that can be sterilized with eachof the portions included therewith. Also the kit 150 can be provided ina sterile manner such that no additional procedures need to occur toprovide a sterile kit.

According to a selected procedure or illustrated in FIGS. 7-9, thedynamic reference frame positioning member 80 can be inserted into aselected portion of the anatomy. A small or stab incision can be formedin an appropriate portion of the anatomy, such as over the posteriorsuperior iliac spine (PSIS) or crest 17 a′ or in any area relative tothe pelvis 17 or the iliac crest 17 a. The incision can be formed in anyappropriate manner, such as with a scalpel or other appropriateinstrument. The incision can also be formed with the dilator 156 and/orcannula 154 being pushed or moved through a skin and/or soft tissuelayer 166.

With reference to FIG. 7, the cannula 154 can be placed percutaneouslypassed through a layer of soft tissue, including skin 166 into the iliac17 a. As discussed above, the iliac 17 a generally includes a PSIS 17 a.The PSIS 17 a′ can be accessed through a posterior portion of thepatient 14 through the skin 166. The cannula 154 can be positionedpercutaneously by positioning the dilator 156 through the cannula 154and simultaneously inserting both members through the soft tissue,including the skin 166.

Both the dilator 156 and the cannula 154 can include cutting orpuncturing edges, which allow it to be passed through the soft tissue,including the skin 166. Positioning the dilator 156 through the cannula154 can assist in assuring that no soft tissue or other material passesinto the cannula 154 prior to a selected procedure. Further, the use ofthe dilator 156 with the cannula 154 can substantially eliminate thenecessity of forming any other incisions through the soft tissueincluding the skin 166 to position the cannula 154 relative to the PSIS17 a′. The use of the cannula 154 and the dilator 156 allows for an easeof the operation further discussed herein.

Once the cannula 154 is positioned next to or relative to the PSIS 17a′, the dilator 156 can be removed from the cannula 154. Once thedilator is removed from the cannula 154, the bore defined by the cannula154 can be used to position a selected member relative to the PSIS 17a′. The portion to be positioned can include the dynamic reference framepositioning member 80. It will be understood that the present exemplarymethod discusses specifically the dynamic reference frame positioningmember 80, but any appropriate member may be used such as the dynamicreference frame positioning members 110, 130.

The dynamic reference frame positioning member 80 can be passed throughthe cannula 154 until it engages or touches the PSIS 17 a′. The dynamicreference frame positioning member 80 can then be driven into the PSIS17 a′ in any appropriate manner. It will be understood that any otherappropriate preparatory steps may also occur. For example, a pilot orpreformed hole may be made in the pelvis 17 prior to positioning thedynamic reference frame positioning member 80. This can allow thedynamic reference frame positioning member 80 to be driven through thepilot hole formed in the pelvis 17. it will be understood, however, thata pilot hole or other preformed opening is not necessary and isdescribed merely as an example.

The tap cap 152 can be selectively interconnected with the dynamicreference frame positioning member 80 and be used, with the impactor 157to drive or impact the dynamic reference frame positioning member 80into the PSIS 17 a′. Any appropriate instrument can be used to assist inthis procedure, such as the hammer or mallet 157. The hammer 157 can beused to impact the proximal or exposed end of the tap cap 152 to drivethe dynamic reference frame positioning member 80 into the bone.

The dynamic reference frame positioning member 80 can be driven in anyappropriate distance, such as until the tap cap 152 engages a portion ofthe cannula 154. Also, the body 82 of the dynamic reference framepositioning member 80 can include selected indicia or markings to assistin determining an amount of movement of the dynamic reference framepositioning member 80 relative to the cannula or the patient 14.Therefore, it will be understood that the bone engaging portion section88 of the dynamic reference frame positioning member 80 can bedetermined to be positioned if the body 82 of the dynamic referenceframe positioning member 80 is substantially similar in length to thecannula 154. It will be understood, however, that any appropriate systemmay be used to determine appropriate positioning of the dynamicreference frame positioning member 80.

Once the dynamic reference frame positioning member 80 has been driveninto the PSIS 17 a′, the tracking sensor 54 a can be interconnected withthe dynamic reference frame positioning member 80. It will beunderstood, however, that the cannula 154 and/or the tap cap 152 canalso be removed before interconnecting the tracking sensor 54 a with thedynamic reference frame positioning member 80. Therefore, for a majorityof the procedure, only the dynamic reference frame positioning member 80is provided percutaneously to engage the PSIS 17 a′.

Also, prior to impacting the dynamic reference frame positioning member80 a fiducial may be used to determine an appropriate location. Furtherthe dynamic reference frame positioning member 80 may act as a fiducialthat is positioned when image data is collected regarding the patient.Thus the tracking sensor 54 a need only be connected to the dynamicreference frame positioning member 80 during an operative procedure.Thus the dynamic reference frame positioning member 80 can be a fiducialfor use in registering the image data or image space to patient space.

Further, if the integral tracking sensor 54 aa is provided, driving thedynamic reference frame positioning member 80 into the PSIS 17 a′ maysubstantially complete positioning the dynamic reference frame.Nevertheless, if the tracking sensor 54 a is provided, it can beselectively interconnected with the dynamic reference frame positioningmember 80. When the tracking sensor 54 a is used it can include alocking screw 170 that can engage the dynamic reference framepositioning portion 100. As discussed above, the dynamic reference framepositioning portion 100 can include a bore 102, which the locking screw170 may engage. The tracking sensor 54 a can include other positioningportions, such as an angle screw, a translation screw, or the like,which can allow for adjustment or positioning the tracking sensor 54 ain any of the 6 degrees of freedom or any selected number thereof.Nevertheless, the tracking sensor 54 a can be interconnected with thedynamic reference frame positioning member 80 in any appropriate manner.

Once the tracking sensor 54 a is interconnected with the dynamicreference frame positioning member 80, (as illustrated in FIG. 1) ifnecessary, the tracking sensor 54 a can be localized or registered withthe navigation system 10. It will be understood that the tracking sensor54 a can be any appropriate dynamic reference frame, such as an opticaldynamic reference frame, an electromagnetic dynamic reference frame, orany appropriate dynamic reference frame. Regardless, the dynamicreference frame positioning member 80 allows the tracking sensor 54 a,54 aa to be held at a selected location relative to a portion of theanatomy for a period during the procedure. The bone engaging portion 88,according to various embodiments, can substantially reduce or eliminaterotation of the dynamic reference frame positioning member 80, andtherefore, the tracking sensor 54 a. Further, the bone engaging portion88 can also substantially reduce or eliminate translation or axialmovement of the dynamic reference frame positioning member 80 and,consequently, motion of the tracking sensor 54 a. Therefore, the dynamicreference frame positioning member 80 can allow for percutaneous holdingof the tracking sensor 54 a relative to the patient 14 for a selectedprocedure. The dynamic reference frame positioning member 80 can holdthe tracking sensor 54 a, 54 aa in any selected amount, such as in sixdegrees of freedom including rotation, translation, axial motion, roll,pitch, and yaw.

After a selected procedure is performed, such as a disc replacement,nucleus replacements, vertebral implants, or other appropriateprocedures, the dynamic reference frame positioning member 80 and thetracking sensor 54 a, 54 aa can be removed.

Although the tracking sensor 54 a and the dynamic reference framepositioning member 80 can be removed in any appropriate manner, thefollowing is an exemplary method. Additionally, if provided, thetracking sensor 54 a can be disconnected from the dynamic referenceframe positioning member 80. The locking screw 170 can be loosened ordisconnected to allow for removal of the tracking sensor 54 a. If thetracking sensor 54 aa is provided, the tracking sensor 54 a need not bepresent and may not need to be removed.

After the tracking sensor 54 a, if provided, is removed the slap hammer158 can engage a portion of the dynamic reference frame positioningmember 80, as illustrated in FIG. 9, such as the dynamic reference frameengaging portion 100 of the dynamic reference frame positioning member80. Once the slap hammer 158 has appropriately engaged the dynamicreference frame positioning member 80, the slap hammer 158 can beoperated in an appropriate manner to remove the dynamic reference framepositioning member 80.

The slap hammer 158 can include a handle 172 that can be operated by auser, such as a physician. An engaging end 174 is provided to engage thedynamic reference frame positioning member 80 in a selected manner. Thehandle 172 can be moved in the direction of arrow B to provide an axialmovement of the slap hammer to withdraw the dynamic reference framepositioning member 80 from the PSIS 17 a′. Once the dynamic referenceframe positioning member 80 has been removed from the PSIS 17 a′, thedynamic reference frame positioning member 80 can be disposed of in anappropriate manner or cleaned and sterilized for further procedures.

Therefore, as discussed above, the dynamic reference frame 54 can bepositioned relative to a selected portion of the patient 14substantially percutaneously, such as through a puncture or through asmall incision. The small incision can be closed in any appropriatemanner, with or without sutures.

Regardless, the disruption of natural tissue with the use of the dynamicreference frame positioning member 80, 110, 130 according to variousembodiments is substantially minimal. Therefore recovery time due to thepositioning of the dynamic reference frame 54 can be substantiallyreduced or eliminated. Also, the ability to drive a dynamic referenceframe positioning member 80 substantially axially into the bone, such asthe iliac 17 can provide for ease of use by a user, such as a physician,and also further reduce trauma to the soft tissue surrounding the areaof positioning of the dynamic reference frame positioning member 80.This can further assist in reducing trauma to the patient 14 and assistin speeding recovery.

It will be understood, that the dynamic reference frame positioningmember 80 can be used to position any appropriate modular trackingsensor 54 a or can include the integral tracking sensor 54 aa. Asdiscussed above, the modular tracking sensor 54 a can be an optical,electromagnetic, acoustic, or any other appropriate dynamic referenceframe. Further, the modular tracking sensor 54 a can be formed in anyappropriate geometry for selected instrumentation. The modular trackingsensor 54 a, using the dynamic reference frame positioning member 80,can be used to perform any appropriate procedure and can be used totrack to any appropriate portion of the anatomy.

For example, the dynamic reference frame positioning member 80 can bedriven into the iliac crest, such as that described above, driven into aportion of the leg, such as a portion of the femur, driven into aportion of the arm, such as the humerus, or the like. The dynamicreference frame positioning member 80, 110 can be sized to allow it tobe interconnected with any appropriate portion of the anatomy anddriving it into the iliac crest is merely exemplary. Regardless, thedynamic reference frame 54 can be positioned relative to a selectedportion of the anatomy to allow for referencing or dynamically trackinga portion of the anatomy during a procedure.

Turning to FIGS. 10 and 11, a dynamic reference frame holding member 200according to various embodiments is illustrated. The dynamic referenceframe holding member 200 can include a plurality of portions that aresimilar to the previously disclosed dynamic reference frame holdingmembers 80, 110, 130. The similar portions will not be described indetail here as they will be understood by one skilled in the art.Briefly, however, the dynamic reference frame holding member 200 caninclude a shaft 202 extending between two ends. Near a first end, a boneengaging portion 204 can be formed. The bone engaging portion 204 caninclude any appropriate engaging portion such as a plurality of fins,points and the like. Nevertheless, the bone engaging portion 204 canhold the dynamic reference frame holding member 200 relatively fixed tothe anatomy 14 in translation, axial movements, rotation, yaw, pitch,and roll.

Near the second end of the shaft 202 is a resiliently deformable member208, such as a spring, a rubber component, or other similar resilientmembers. Further, an engaging pin 206 is formed to extend from the shaft202. It will be understood that the engaging pin 206 can extend from aplurality of positions or include a plurality of extending portions.Nevertheless, a single extending portion is illustrated for clarity ofthe current discussion.

The dynamic reference frame holding member 200 can be inserted in amanner substantially similar to that discussed above. Nevertheless, atap cap 152′ can include a slot or passage 210 that is able to extendover a proximal or second end of the dynamic reference frame holdingmember 200 so as not to engage the engaging pin 206 in a substantialmanner. Therefore the tap cap 152′ can engage mostly the resilientportion 208 rather than directing forces on the engaging pin 206.Therefore the dynamic reference frame holding member 200 can be driveninto a selected portion of the anatomy, such as the PSIS 17 a′ asdiscussed above. The dynamic reference frame holding member 200 caninclude an integral or single piece tracking sensor 54 aa. Nevertheless,the engaging pin 206 can be used to engage a modular tracking sensor 54a′ illustrated in FIG. 11. The modular tracking sensor 54 a′ can includean engaging shaft 212 that can include a portion that is operable tomove over or pass over the second end of the dynamic reference frameholding member 200. An opening 214 can be defined in the shaft portion212 of the modular tracking sensor 54 a′ to allow the engaging pin 206to move into a selected portion of the opening 214.

When positioning the tracking sensor 54 a′ relative to the dynamicreference frame holding member 200, the tracking sensor 54 a′ can have aforce applied to it to deform the resilient member 208. The modulartracking sensor 54 a′ can then be rotated to move the engaging pin 206to a selected portion of the opening 214. Once the engaging pin 206 ispositioned in a selected area of the opening 214, the applied force tothe modular tracking sensor 54 a′ can be removed. The resilient member208 can then push against the modular tracking sensor 54 a′ to move themodular tracking sensor 54 a′ in a manner that allows the engaging pin206 to engage in an engaging portion 216 of the opening 214.

Therefore the modular tracking sensor 54 a′ can be easily and quicklyinterconnected with the dynamic reference frame holding member 200.Further, the modular dynamic reference frame 54 a′ can be easily andrepeatedly interconnected with the dynamic reference frame holdingmember 200 during a selected procedure prior thereto, or afterwards. Theengaging pin 206, in cooperation with the resilient member 208 and theengaging section 216, can allow for ease of attachment in a quickmanner. It also allows for ease of substantial repeatability of theengagement. Therefore, the modular tracking sensor 54 a′ can be easilyinterconnected with the holding member 200. Nevertheless, it will beunderstood that a modular tracking sensor can be interconnected with anyappropriate dynamic reference frame holding member 80, 110, 130 forvarious purposes.

Further areas of applicability of the present teachings will becomeapparent from the detailed description provided above. It should beunderstood that the detailed description and specific examples, whileindicating various embodiments, are intended for purposes ofillustration only and are not intended to limit the scope of theteachings.

What is claimed is:
 1. A surgical navigation system for use in asurgical procedure on an anatomy including a bone, comprising: atracking system; a dynamic reference frame tracking sensor operable tobe tracked by the tracking system as a dynamic reference frame; adynamic reference frame positioning member having a substantiallynon-cylindrical bone engaging portion including at least one armextending from a central region that is configured to be axially driveninto the bone to at least resist rotation of the dynamic reference framepositioning member about a long axis of the dynamic reference framepositioning member; wherein the dynamic reference frame tracking sensoris attached to the dynamic reference frame positioning member; whereinthe dynamic reference frame positioning member is operable to engage abone in the anatomy in a selectively fixed manner at least by beingimpacted into the bone in the axial direction to hold the dynamicreference frame tracking sensor in a selected position relative to thebone.
 2. The system of claim 1, wherein the at least one arm includes atleast four arms extending radially from the central region.
 3. Thesystem of claim 2, wherein the substantially non-cylindrical boneengaging portion has a cruciform cross-section when taken substantiallyperpendicular to the long axis of the dynamic reference framepositioning member defined by the at least four arms extending radiallyfrom the central region.
 4. The system of claim 1, wherein the dynamicreference frame positioning member further comprises: a sensor holdingportion that is at a fixed position relative to the substantiallynon-cylindrical bone engaging portion.
 5. The system claim 1, whereinthe dynamic reference frame positioning member further comprises: a pinextending transverse to the long axis of the dynamic reference framepositioning member; and a resilient member to bias the dynamic referenceframe tracking sensor to engage the pin.
 6. The system of claim 1,wherein the dynamic reference frame positioning member includesincorporated therein the dynamic reference frame tracking sensor suchthat the dynamic reference frame tracking sensor is at a fixed positionrelative to the substantially non-cylindrical bone engaging portion. 7.The system of claim 1, further comprising: a cannula adapted to passthrough soft tissue relative to the bone adapted to assist in passage ofthe dynamic reference frame positioning member towards and into thebone; a dilator configured to initially pass through the cannula priorto passing the dynamic reference frame positioning member passingtowards and into the bone through the cannula; and an impactioninstrument adapted to impact the dynamic reference frame positioningmember into the bone through the cannula; wherein the cannula and thedilator are adapted to prepare the soft tissue for passage of thedynamic reference frame positioning member towards and into the bone;wherein the dynamic reference frame positioning member includes indiciato assist in determining an amount of movement of the dynamic referenceframe positioning member relative to at least one of the cannula or thebone.
 8. A surgical navigation system for use in a surgical procedure onan anatomy including a bone, comprising: a tracking system; a dynamicreference frame tracking sensor operable to be tracked by the trackingsystem as a dynamic reference frame; and a dynamic reference framepositioning member having: a bone engaging portion, wherein the boneengaging portion has at least a first section that has at least a firstarm and a second arm that extend transverse to a long axis of thedynamic reference frame positioning member and that is configured to beaxially driven into the bone to at least resist rotation of the dynamicreference frame positioning member about the long axis, and a sensorholding section, wherein the dynamic reference frame tracking sensor isconfigured to removably engage the sensor holding section in a fixedposition relative to the bone engaging portion; wherein the dynamicreference frame positioning member is operable to engage a bone in theanatomy in a selectively fixed manner at least by being impacted intothe bone in the axial direction to hold said dynamic reference frametracking sensor in a selected position relative to the bone.
 9. Thesystem of claim 8, wherein the dynamic reference frame tracking sensorincludes a locking screw to engage the sensor holding section.
 10. Thesystem of claim 8, wherein the sensor holding section includes a pinextending transverse to the long axis of the dynamic reference framepositioning member and a resilient member to bias the dynamic referenceframe tracking sensor to engage the pin; wherein the dynamic referenceframe tracking sensor includes an opening and an engaging portion;wherein the pin is operable to move through the opening and engage theengaging portion of the dynamic reference frame tracking sensor when thedynamic reference frame tracking sensor is biased by the resilientmember.
 11. The system of claim 8, wherein the first arm and the secondarm are substantially thin relative to the remaining portion of thedynamic reference frame positioning member.
 12. The system of claim 8,wherein the bone engaging portion further includes a third arm and afourth arm; wherein all of the first arm, the second arm, the third arm,and the fourth arm together form a cruciform configuration extendingfrom an end region of the dynamic reference frame positioning member andforming a terminal end of the dynamic reference frame positioningmember.
 13. The system of claim 8, wherein the bone engaging portionfurther includes a third arm and a fourth arm, and an extending portion;wherein all of the first arm, the second arm, the third arm, and thefourth arm extend radially from the extending portion.
 14. The system ofclaim 13, wherein the extending portion includes a smooth portion thatextends beyond all of the first arm, the second arm, the third arm, andthe fourth arm along the long axis and forms a terminal end of thedynamic reference frame positioning member.
 15. The system of claim 8,further comprising: a removal tool to engage the dynamic reference framepositioning member to axially remove the bone engaging portion from thebone after it is impacted into the bone.
 16. A surgical navigationsystem for use in a surgical procedure on an anatomy including a bone,comprising: a tracking system; a dynamic reference frame tracking sensoroperable to be tracked by the tracking system as a dynamic referenceframe; and a dynamic reference frame positioning member having: a boneengaging portion, wherein the bone engaging portion has at least a firstsection that has at least a first arm and a second arm that extendtransverse to a long axis of the dynamic reference frame positioningmember and that is configured to be axially driven into the bone to atleast resist rotation of the dynamic reference frame positioning memberabout the long axis, and a sensor holding section having a pin extendingtransverse to the long axis of the dynamic reference frame positioningmember, wherein the dynamic reference frame tracking sensor isconfigured to removably engage the sensor holding section in a fixedposition relative to the bone engaging portion; and a cap having a pinpassage to allow the pin to pass relative to the cap during an impactionof the dynamic reference frame positioning member; wherein the cap isconfigured to be directly impacted and transfer an impaction force tothe dynamic reference frame positioning member; wherein the pin passagelimits contact and an impaction force applied to the pin duringimpaction of the dynamic reference frame positioning member; wherein thedynamic reference frame positioning member is operable to engage a bonein the anatomy in a selectively fixed manner at least by being impactedinto the bone in the axial direction to hold said dynamic referenceframe tracking sensor in a selected position relative to the bone.
 17. Amethod for using a surgical navigation system during surgical procedureon an anatomy including a bone, comprising: tracking a dynamic referenceframe tracking sensor with a tracking system as a dynamic referenceframe; and providing a dynamic reference frame positioning memberextending along a long axis and formed with: a bone engaging portion,wherein the bone engaging portion has at least a first section that hasat least a first arm and a second arm that extend transverse to the longaxis and is configured to be axially driven into the bone to at leastresist rotation of the dynamic reference frame positioning member aboutthe long axis, and a sensor holding section configured to engage thedynamic reference frame tracking sensor in a fixed position relative tothe bone engaging portion; wherein the dynamic reference framepositioning member is operable to engage a bone in the anatomy in aselectively fixed manner at least by being impacted into the boneaxially in a direction along the long axis to hold said dynamicreference frame tracking sensor in a selected position relative to thebone.
 18. The method of claim 17, further comprising: axially impacting,along the long axis, at least the bone engaging portion of the provideddynamic reference frame positioning member into the bone along the longaxis to penetrate the bone with at least the bone engaging portionincluding the first arm and the second arm to at least rotationally fixthe provided dynamic reference frame positioning member relative to thebone.
 19. The method of claim 18, further comprising: connecting thedynamic reference frame tracking sensor to the driven dynamic referenceframe positioning member; performing a procedure relative to the drivendynamic reference frame positioning member; and after performing theprocedure, engaging the driven dynamic reference frame positioningmember to remove at least the bone engaging portion from the bone. 20.The method of claim 17, wherein providing the dynamic reference framepositioning member with the bone engaging portion further includes atleast a third arm and a fourth arm such that the first arm, the secondarm, the third arm, and the fourth arm form a cruciform configuration incross-section substantially transverse to the long axis.
 21. The methodof claim 17, further comprising: forming the provided dynamic referenceframe positioning member to incorporate the dynamic reference frametracking sensor as a single member; wherein the dynamic reference frametracking sensor is fixed relative to the bone engaging section.